How to make smooth curves and rough edges
Here's one approach:




6-sided circle
Fill (F), and Knife cut (K) using Ctrl to hit center of edges
Drag out back edges. (Scale thinner if you like)
Add loop cuts (CtrlR). Assuming you might want to bend the aerofoil.
Extrude (E) perimeter edges
Maybe pull out the middle edges of the side? and put in a holding edge-loop (CtrlR).
Add a Mirror modifier,
And a Subsurf modifier.